Question

Find the length of the radius of the following circle.

x² + y² = 16

4
8
16

Answer 1

Standard form of a circle:
\[(x-h)^{2}+(y-k)^{2}=r^{2}\]

Your circle:
\[(x-0)^{2}+(y-0)^{2}=(\sqrt{16})^{2}\]

So:
\[r=\sqrt{16}=4\]